It t's into the top line of the tranny cooler lines going to the radiator. Do not run it off the bottom line. The radiator warms as well as cools the fluid. Too cool fluid=rough shifting.
You want one with the least amount of flow resistance. Usually around 1" thick or more. It's more about efficency of cooling than size. Smaller, crossflow coolers are better than larger tube-style coolers.

Is that the trans cooler that comes with the tow package, or is it an aftermarket? Also what is that trans cooler rated at in terms of towing pounds/capacity?

Thanks

Ya it comes with the towing package. The size of cooler doesn't determine the capacity that you can tow. They say yuo can tow 6500lb with the towing package, but I seen tests where someone hooked in a trans temp gauge and with no load they were pulling some high numbers in the city.

Is that the trans cooler that comes with the tow package, or is it an aftermarket? Also what is that trans cooler rated at in terms of towing pounds/capacity?

Thanks

The aftermarket ones are sometimes listed by weight. The Tacoma is rated for 5000-6500lbs for the V6 depending on equipment. I'd get the biggest most efficient cooler you can get. The tube style are the cheaper ones and don't work as good as the plate style. You can't cause any damage by having too big a cooler.

If you look at Etrailer.com they have a good selection. When I pick one up it'll be a 'class V' plate style. If you go to an AN style hookup keep in the mind the fittings are expensive and add up fast.